Note: Descriptions are shown in the official language in which they were submitted.
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FACE SEAL FOR RESPIRATOR
Technical Field
The present invention relates to face seals for respirators and more
particularly to face seals that seal the interface between a respirator and
the face of
a wearer to prevent contaminated air from entering the wearer's breathing
zone.
Background of the Invention
Respirators are commonly worn by people working in areas where the air
to may be contaminated with toxic or noxious substances such as airborne
particulates, gases, and vapors. For example, the air in a sanding or grinding
area
may contain airborne dust particles, the air in a painting area may contain
solvent
vapors or droplets of paint, and the air in a welding area may contain fumes
that
would be harmful to inhale. People working in these areas will often wear a
15 respirator that either filters contaminated air before it reaches the
breathing zone of
the wearer or supplies the user with uncontaminated air from a remote air
source.
The type of respirator used in a particular environment depends on the
amount and type of protection required by the wearer. When it is desirable to
protect both the eyes and respiratory system of a wearer, a device commonly
2o referred to as a "loose fitting face piece" is often used. The term "loose
fitting face
piece" defines a classification of the American National Standards Institute
{ANSI)
for a respiratory protective system in which a face shield or some type of
enclosure
about the face is designed to form a partial seal with the face. Loose fitting
face
pieces typically do not cover the neck and shoulders of the wearer and may
include
25 a helmet or other headpiece to protect the head from flying or falling
objects. In
many cases, a face shield is designed to rotate with respect to the headgear
between
a position covering the face and eyes and a position away from the face.
In order to help prevent contaminated air from reaching the face and eyes
of the wearer, loose fitting face pieces are often provided with a face seal.
When
3o the respirator is sealed in this way, the air pressure inside the mask can
be either
negative or positive as compared to the surrounding environment. A negative
pressure respirator is designed to have a lower pressure inside the mask than
the
surrounding ambient air and requires an air-tight seal between the mask and
the
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face of the wearer to prevent contaminated air from being pulled into the
respirator. A positive pressure respirator is designed to have a higher
pressure
inside the mask than the surrounding air and commonly has at least one small
opening to allow excess air that is under pressure in the mask to escape into
the
surrounding ambient air.
There are several known face seal designs used with loose fitting face
pieces. One common face seal design includes a piece of fabric having one edge
attached to the sides and lower portion of a rigid face shield piece and
having
elastic material along the other edge. When a user pulls the rigid face shield
piece
10 down to a position covering the face, the elastic edge typically contacts
the front of
the user's chin and mouth area. For user comfort and in order to assist in
forming
a proper seal, the user must reach up under the face shield piece to pull the
elastic
edge of the fabric underneath the chin. This process may be difficult and
inconvenient for the user, particularly if that person needs to use both hands
for
15 some other task, or if the person is wearing cumbersome work gloves.
This face seal design can also be inconvenient for users who wear glasses
under the face shield, because the elastic edge of the fabric can interfere
with the
corner of the glasses when the face shield is being pulled down over the face.
This
contact between the elastic and glasses can dislocate the glasses or cause the
2o glasses to fall from the user's face.
Another face seal design involves the use of a U-shaped flange made of
rubber or other resilient material positioned on the inside of the face shield
to
contact the cheeks and chin of the wearer and provide a seal. For example, U.
S.
Patent No. 4,280,491 (Berg et al.), which is commonly owned by the assignee of
2s the present invention, describes a respirator having U-shaped sealing means
formed of a resilient material, such as foam, fastened along the peripheral
edge of a
frame to seal the face shield assembly along the sides and across the chin of
the
user's face. While these face seals can provide an adequate seal for some
users,
the seals may not be easily adaptable to accommodate different face and head
3o sizes. Thus, these face seals may not be interchangeable between users.
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Summary of the Invention
The present invention provides a face seal for use with respirators which
self adjusts to the face of the wearer when the face shield is lowered to its
working
position. Flexible face seal segments provide the correct positioning of the
face
seal for both comfort and respiratory protection of the wearer.
In one aspect of this invention a face seal assembly for respirators is
provided, wherein the assembly comprises a generally U-shaped frame having a
bottom portion and first and second side portions spaced from each other and
extending in a generally upward direction from the bottom portion. The
assembly
to further includes a first face seal segment attached to the bottom portion
at a point
closer to the second side portion than the first side portion and to the first
side
portion at a point above the bottom portion, and a second face seal segment
attached to the bottom portion at a point closer to the first side portion
than the
second side portion and to the second side portion at a point above the bottom
15 portion. The present invention also includes within its scope that the
first face seal
segment overlaps the second face seal segment and that the first and second
face
seal segments each include an elastic piece.
In this face seal assembly, at least a portion of the first face seal segment
may extend beyond the elastic piece of the first face seal segment to form a
first
2o face seal flap and at least a portion of the second face seal segment may
extend
beyond the elastic piece of the second face seal segment to form a second face
seal
flap. In at least one embodiment, the first and second face seal segments are
made
of cloth, which may be nonwoven fabric, a woven fabric, a flame-retardant
material, or an elastic material. The cloth of the first and second face seal
25 segments may also be nonporous to prevent the movement of air through the
cloth.
In another aspect of the present invention, a respirator is provided, wherein
the respirator comprises a helmet, a face shield assembly comprising a face
shield
frame attached to the helmet and a face shield mounted therein, and a face
seal
assembly attached to the face shield assembly. In this aspect of the
invention, the
3o face seal assembly comprises a generally U-shaped face seal frame having a
bottom portion and first and second side portions spaced from each other and
extending in a generally upward direction from the bottom portion, a first
face seal
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segment attached to the bottom portion at a point closer to the second side
portion
than the first side portion and to the first side portion at a point above the
bottom
portion, and a second face seal segment attached to the bottom portion at a
point
closer to the first side portion then the second side portion and to the
second side
portion at a point above the bottom portion. When the face shield assembly is
positioned over the face of a wearer, the first face seal segment contacts a
first side
of the wearer's face, the second face seal segment contacts a second side of
the
wearer's face, and the first and second face seal segments cross under the
wearer's
chin, thereby generally sealing the wearer's face from air outside the
respirator.
Brief Description of the Drawings
The present invention will be further explained with reference to the
appended Figures, wherein like structure is referred .to by like numerals
throughout
the several views, and wherein:
Figure 1 is a perspective view of one embodiment of a respirator according
to the present invention;
Figure 2 is a side view of a respirator according to the present invention,
showing a face shield assembly in its operational position and also showing
the
face shield assembly in its raised position in dotted lines;
2o Figure 3 is a perspective view of the face seal assembly of Figure l;
Figure 4 is a front view of a face seal assembly including the face seal of
the present invention;
Figure S is a front view of the face seal assembly of Figure 4, incorporating
the face seal of the present invention with the partial insertion of a human
head;
2s Figure 6 is a front view of the face seal assembly of Figures 4 and 5,
incorporating the face seal of the present invention with the human head
inserted
further than in Figure 5; and
Figure 7 is a perspective view of another embodiment of a respirator
according to the present invention.
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Detailed Description of the Preferred Embodiments
Referring now to the Figures, wherein the components are labeled with like
numerals throughout the several Figures, and initially to Figures 1 and 2, one
preferred embodiment of a respirator or loose fitting face piece 10 is
illustrated
5 which basic components include a helmet or headpiece 12, a face shield
assembly
14 rotatably attached to helmet 12, and a face sealing assembly 20. Helmet 12
is
typically hemispherical in shape and comprises an inner shell 22 spaced from
an
outer shell 24, where a generally dome-shaped passageway or chamber 26 is
defined between shells 22 and 24. In one preferred configuration, helmet 12
and
to chamber 26 further comprise a rear opening or receptacle 28 designed to
accept an
air supply hose (not shown), and a front opening 30 designed to allow the
supplied
air to escape into the face area and breathing zone of the wearer. When
assembled,
the outer shell 24 is superposed over the inner shell 22 and the periphery of
these
shells are typically sealed between the rear opening 28 and the front opening
30 to
15 prevent undesirable leakage of air from the sides of the helmet. In
operation, air is
supplied under pressure to the rear opening 28. The air moves into the rear
area of
the chamber 26 nearest the rear opening 28 and toward the front area of the
chamber 26. The air then exits the chamber 26 through the front opening 30 and
into the breathing zone of the wearer. Examples of helmets having an air
2o passageway or chamber are shown in U.S. Patent Nos. 4,280,491 (Berg et al.)
and
4,136,688 (Gorman). It will be appreciated by those skilled in the art that
this
description directed to loose fitting face pieces is descriptive and is not
intended to
be limited to loose fitting face pieces.
The face shield assembly 14 is preferably attached to the sides of the
25 helmet 12 by a hinge assembly 32. As shown in Figure 2, the hinge assembly
32
allows the wearer to rotate the face shield assembly 14 away from the face
(illustrated in dotted lines and hereinafter referred to as the uppermost
position).
With continuing reference to Figures l and 2, the hinge assembly 32 also
allows
rotation of the face shield assembly 14 down over the face of the user when
the
3o respirator is in use (hereinafter referred to as the lowermost or working
position).
The hinge assembly 32 may be designed so that the face shield assembly 14 can
be
fixed at different positions between the uppermost and lowermost positions, or
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may be freely rotatable between these positions. It is known that the face
shield
may be rotatably attached to the helmet in various different ways, all of
which are
considered to be within the scope of this invention. It is further understood
that the
face shield assembly may be fixed so that it does not rotate with respect to
the
5 helmet. In this case, the hinge assembly 32 may be eliminated from the
respirator.
One configuration of the face shield assembly 14 includes a face shield
frame 16 as shown in Figure 1. The frame 16 preferably comprises a top frame
portion 34, two side frame portions 36, 38 spaced from each other, and a lower
frame portion 40 connecting frame portions 36, 38. The top frame portion 34
1o preferably extends across the lower edge of the front of the helmet 12 when
the
face shield assembly 14 is in its lowermost position, and may be provided with
a
seal (not shown) between the top frame portion 34 and the helmet 12 to assist
in
preventing air from entering or escaping the breathing zone of respirator.
Side
frame portions 36, 38 extend from top frame portion 34 in a generally downward
is direction and away from the face of the wearer. Lower frame portion 40
connects
the bottom edges of side frame portions 36, 38 and is generally parallel to
the top
frame portion 34. Thus, the frame 16 comprises a generally U-shaped lower
portion including side frame portions 36, 38 extending from a lower frame
portion
40. An opening 42 is provided between the portions of the frame 16, wherein
the
20 opening 42 is sufficiently large to provide the wearer with a substantially
unobstructed forward and peripheral field of view. A generally transparent
face
shield 18 is positioned within the opening 42 to protect the face of the
respirator
wearer. The face shield 18 is preferably made of a tough, generally
transparent
flexible plastic material such as polycarbonate, cellulose, acetate, acrylic,
2s polyester, or the like, and is designed to fit tightly within the face
shield frame 16.
As described above, when the face shield assembly 14 is in its lowermost
position,
the side frame portions 36 and 38 are spaced away from the sides of the user's
face
and the lower frame portion 40 is spaced away from the chin area of the user.
It is
understood that the face shield assembly 14 may be a welding shield, wherein
the
3o face shield frame 16 and the face shield 18 are manufactured from materials
that
are appropriate for use in welding environments.
6
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In order to seal the areas between of the face shield assembly 14 and the
face of the wearer, face shield assembly 14 is provided with a face seal
assembly
20. In one preferred embodiment, illustrated in Figures 3 and 4, the face seal
assembly 20 generally comprises a face seal frame 44 and two face seal
segments
46, 48. More specifically, face seal frame 44 has a generally U-shaped
configuration, including two side frame portions 50, SZ that extend in a
generally
upward direction from a bottom frame portion 54. The frame 44 may be designed
to generally follow the shape and size of the face shield frame 16 so that the
frame
44 can be tightly attached to the face shield assembly 14 with few or no
openings
1o for air leakage between the face shield frame 16 and the face seal frame
44. The
frame 44 further comprises connectors 56 to attach the face seal frame 44 to
the
face shield frame 16 near the top portions of each of the side frame portions
50, 52.
In this embodiment, the connectors 56 are illustrated as pins that extend from
the
side frame portions S0, 52, however, any conventional connection method is
15 considered to be within the scope of this invention. Preferably, the
connectors 56
allow for secure attachment of the face seal frame 44 to the face shield frame
16,
while permitting easy removal of the frame 44 when desired.
It is preferred that the face seal frame 44 be generally concave in cross
section, as shown generally in Figure 3. This cross-section advantageously
2o provides additional space for the user's face to move from side to side
within the
respirator when face seal frame 44 is attached to face shield frame 16 and
positioned in front of the user's face.
Figures 3 and 4 also illustrate one arrangement of the face seal segments
46, 48 as positioned within face seal frame 44 before contacting a wearer's
face or
2s after removal from a wearer's face. In this arrangement, the first face
seal segment
46 is preferably attached to an upper part of the side face seal frame portion
50 and
to the bottom frame portion 54 at a point adjacent the opposite side face seal
frame
portion 52. Similarly, the second face seal segment 48 is preferably attached
to an
upper part of the side face seal frame portion 52 and to the bottom frame
portion
30 54 at a point adjacent the side face seal frame portion 50. Thus, the
points where
each of the segments 46, 48 are attached to the bottom frame portion 54 are
preferably spaced from each other. It is understood that the point on the side
frame
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portions 50, 52 where the first and second face seal segments 46, 48 are
attached
can be any point above the point where each of these face seal segments are
attached to bottom frame portion 54. It is preferable, however, that the point
where
each of the face seal segments 46, 48 is attached to the side frame portions
50, 52
5 is spaced as far as possible from the bottom frame portion 54, in order to
span a
greater portion of the frame 44 and thereby provide a larger amount of sealing
protection. Thus, the face seal segments 46, 48 at least partially overlap
each other
to provide the face sealing capability of the present invention.
In accordance with the present invention and as best illustrated in Figure 4,
to at least one strip of elastic material 60 is attached to the face seal
segment 46 and at
least one strip of elastic material 62 is attached the face seal segment 48.
In the
preferred embodiment, the face seal segments 46, 48 are a flexible material,
such
as cloth, and the elastic strips 60, 62 are sewn thereto. Elastic strips 60,
62 should
be sufficiently elastic to allow separation of the face seal segments 46, 48
from
15 each other, while providing a comfortable seal around the wearer's face.
The
elastic strips 60, 62 are preferably positioned on the face seal segments 46,
48 as
shown in Figure 4. That is, the elastic strip 60 is spaced from an edge 64 of
the
face seal segment 46 so that a loose portion or flap 68 extends between the
elastic
strip 60 and the edge 64. Similarly, the elastic strip 62 is spaced from an
edge 66
20 of the face seal segment 48 so that a loose portion or flap 70 extends
between the
elastic strip 62 and the edge 66. The desirability of these flaps 68, 70 will
be
described below.
Figure 5 shows the separation of face seal segments 46, 48 of Figure 4
when a wearer's face initially contacts the face seal segments. In operation,
this
25 occurs when the wearer rotates the face shield assembly 14 down toward its
working position. Alternatively, it is understood that the face shield
assembly 14
may already be in its lowermost or working position when the wearer initially
places the helmet 12 on his or her head. As shown in Figure 5, the face seal
segment 46, which is closer to the wearer's face, first contacts the face of
the
3o wearer and is pushed by the face toward the side frame portion 50.
Similarly, the
face seal segment 48, which is in overlapped relation to face seal segment 46,
is
pushed toward the side frame portion 52. In accordance with the invention, the
8
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face seal segments 46 and 48 are not attached to each other where they cross
or
overlap so that they can easily separate the necessary distance as the face
shield is
moved toward the working position and the face contacts these segments. Thus,
the face seal assembly 20 can accommodate various face shapes and sizes
without
s adjusting the face seal segments.
Figure 6 illustrates the face seal segments 46, 48 as they seal around the
wearer's face when the face shield assembly 14 is in its working or lowermost
position. This position is similar to that described above with respect to
Figure 5,
except that the face seal segments 46, 48 are further pushed toward the side
face
1o seal frame portions 50, 52 and side face shield frame portions 36 and 38
(not
shown in this figure), respectively. In most cases, the elastic portions 60,
62 are
stretched by the insertion of the wearer's face between segments 46, 48, which
helps to form the proper seal for operation of the respirator. Further, it is
preferred
that the flap portions 68, 70 extend onto the face of the wearer to better
seal against
15 air filtration into the wearer's breathing zone. In other words, when the
face shield
assembly 14 is positioned over the face of a wearer, the first face seal
segment 46
contacts the first side of the wearer's face, the second face seal segment 48
contacts the second side of the wearer's face, and the first and second face
seal
segments 46, 48 cross under the wearer's chin, thereby generally sealing the
2o wearer's face from air outside the respirator. The flaps 68, 70 are
desirable to form
an additional barrier to the entrance of contaminants, particularly for
wearers with
smaller face sizes.
In the preferred embodiment, the face seal segments 46, 48 are made of a
flexible material to allow the face seal to function as described above. The
actual
25 material chosen for the segments 46, 48 may vary widely, where different
properties may be desirable for different respirator applications. For
example, the
material should be sufficiently flexible to allow the face seal segments 46,
48 to
separate from each other, but should also be sufficiently stiff so that the
flap
portions 68, 70 can rest against the wearer's face without falling away from
the
3o face. The material selected can be a woven fabric or a nonwoven material.
It is
often desirable that the material also be nonporous to prevent air outside the
respirator to move through the material and into the breathing zone of the
9
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respirator. The material may also be washable so that the face seal segments
may
be reusable after washing. It may further be desirable that the material is
fire-
retardant, particularly when the respirator will be used in environments such
as
welding applications. One example of a preferred material that is relatively
comfortable, lightweight, nonporous, and fire-retardant is fabric commercially
available from the DuPont Corporation of Willmington, Delaware, under the
trade
designation "Sontara."
Alternatively, the face seal segments 46, 48 may be made of an elastic
material, such as rubber. In this case, the elastic in the material may
provide the
1o necessary elasticity for proper functioning of the face seal segments and
the elastic
pieces 60, 62 may therefore be unnecessary.
The face seal segments 46, 48 may be attached to the face seal frame 44 by
various attachment means. The attachment means chosen may allow the face seal
segments to be easily removed from the face seal frame for replacement with
new
1s face seal segments. For example, the face seal segments may be provided
with
holes near their outer edges to match with pegs or protrusions from the face
seal
frame so that the holes can be placed over the protrusions for attachment
thereto
(not shown). For another example, the edge of the face seal segments 46, 48
closest to their respective side frame portions 50, 52 may include an elastic
portion
2o to hold these segments against the frame portions. Alternatively, the face
seal
segments may be attached to the face seal frame by more permanent methods,
such
as applying an adhesive between the face seal frame and the outer edges of the
face
seal segments.
In some cases, it may be desirable for the face seal segments 46, 48 to be
25 shaped so that there is a flexible portion that extends above the elastic
strips 60, 62,
hereinafter referred to as temple portions 72, 74. These temple portions 72,
74 are
attached to the upper portion of the side face seal frame portions 50, 52,
respectively, to seal against the upper part of the face (i. e., near the
temples of the
wearer) when the face shield assembly is in the working position. These temple
3o portions advantageously provide sealing of wearer's upper face area, while
allowing the wearer to move face shield assembly 14 from its uppermost
position
to its working position without substantial interference between face seal
segments
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46, 48 and the face or glasses of the wearer. In operation, the temple
portions 72,
74 should be sufficiently free from the face seal frame 44 so that they can
move
away from the wearer's face when the face shield assembly 14 is lowered. At
least
some part of each of the temple portions 72, 74 may also be reinforced with
another piece of material or the like (not shown) in order to provide
additional
sealing capabilities in the upper area of the wearer's face.
While the embodiment of Figure 1 shows face seal segments attached to a
separate face seal frame that is attached to a face shield frame, it is also
contemplated that these segments instead be attached directly to the face
shield
to frame. Figure 7 illustrates this embodiment of the face shield assembly 14,
where
face seal segments 46 and 48 are attached directly the face shield frame 16.
More
specifically, the face seal segment 46 is attached to the upper part of the
side frame
portion 36 and to the lower frame portion 40 adjacent the opposite side frame
portion 38. The face seal segment 48 is attached to the upper pan of the side
frame
15 portion 38 and to the lower frame portion 40 adjacent the opposite side
frame
portion 36. In all other respects, it is desirable that the face seal assembly
have the
characteristics of the face seal assembly described above with respect to
Figures 1
through 6.
It is also within the scope of this invention that the face seal segments are
2o attached to the outer edge of a lens that does not have a separate frame
(not
shown). In this case, the respirator does not have the type of face shield
frame
described above. Instead, the lens is attached to an air supply device and the
outer
edge of the lens is actually the frame that supports the face seal segments in
the
configuration of the present invention.
25 The respirator 10 may be a powered air respirator, such as a self contained
battery powered unit, where the respirator may be provided with a filter (not
shown) to filter incoming contaminated air before it reaches the breathing
zone of
the wearer. Alternatively, the respirator 10 may be a supplied air respirator,
where
the supplied air is prefiltered so that no additional air filters may be
necessary. In
3o addition, while the face seals described above are primarily designed for
use with a
positive pressure respirator, it is also contemplated that the face seal may
be used
for different respirator classifications.
1l
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The present invention has now been described with reference to several
embodiments thereof. The foregoing detailed description has been given for
clarity of understanding only. No unnecessary limitations are to be understood
therefrom. It will be apparent to those skilled in the art that many changes
can be
5 made in the embodiments described without departing from the scope of the
invention. For instance, devices such as medical masks are also contemplated.
Thus, the scope of the present invention should not be limited to the
structures
described herein, but only by the structures described by the language of the
claims
and the equivalents of those structures.
to
12
